/* RCSid $Id: pmaprand.h,v 2.4 2015/08/18 18:45:55 greg Exp $ */
#ifndef PMAPRAND_H
#define PMAPRAND_H

/* 
   ==================================================================
   Random number generators for photon distribution

   Roland Schregle (roland.schregle@{hslu.ch, gmail.com})
   (c) Fraunhofer Institute for Solar Energy Systems,
   (c) Lucerne University of Applied Sciences and Arts,
   supported by the Swiss National Science Foundation (SNSF, #147053)
   ==================================================================
   
   $Id: pmaprand.h,v 2.4 2015/08/18 18:45:55 greg Exp $
*/



/* According to the analytical validation, skipping numbers in the sequence
   introduces bias in scenes with high reflectance. We therefore use
   erand48() with separate states for photon emission, scattering, and
   russian roulette. The pmapSeed() and pmapRandom() macros can be adapted
   to other (better?) RNGs. */   

#if defined(_WIN32) || defined(BSD)
   /* Assume no erand48(), so use standard RNG without explicit multistate 
      control; the resulting sequences will be suboptimal */      
   #include "random.h"
   
   #define pmapSeed(seed, state) (srandom(seed))
   #define pmapRandom(state)     (frandom())
#else
   #define pmapSeed(seed, state) (state [0] += seed, state [1] += seed, \
                                  state [2] += seed)
   #define pmapRandom(state) erand48(state)
#endif

   
extern unsigned short partState [3], emitState [3], cntState [3],
                      mediumState [3], scatterState [3], rouletteState [3],
                      randSeed;

#endif